The present invention relates to a seal member for impeding leakage of fine particles. More particularly, the present invention relates to a seal member for impeding leakage of toner in a printing apparatus such as a copier, a printer or a fax machine.
Printing apparatuses using toner are less costly to operate in comparison to other printing apparatuses such as thermal printing apparatuses. As a result, toner-based printing apparatuses have been widely accepted for both business and personal use.
Typically, toner-based printing apparatuses include a developer. The developer has a housing in which the toner and a cylindrical developer roller are accommodated. In an interior of the housing, the toner first adheres to the surface of the developer roller and is then transferred from the developer roller to the outer circumferential surface of a drum coated with photosensitive material, as the roller rotates. The toner is then electrically attracted to a latent image formed on the outer surface of the drum after exposure by a light beam from an exposure unit. This produces a reversed image, made of the toner, on the photosensitive material. The reversed image is then transferred to paper by a transfer unit and is fused to the paper to produce a print.
In the interior of the developer, a cylindrical space or clearance in which the toner is accommodated is defined between the developer roller and the inner circumferential surface of the housing. Seal members are attached to both ends of the housing to engage the respective ends of the roller. The seal members seal the clearance to impede leakage of the toner from the housing.
Prior art seal members have an engaging layer for slidably engaging with the respective ends of the roller and a support layer located under the engaging layer and attached to the inner surface of the housing. The engaging layer includes felt made of fluororesin fibers. The support layer includes laminated sponge layers.
Since the engaging layer of the prior art seal member is made from felt, the engaging layer has a relatively low durability, so that if the engaging layer is used for a long period of time, many fibers are depilated from the engaging layer or deformed. Because of this disadvantage, the effectiveness of the seal member gradually deteriorates, and the toner may leak from the developer.
Furthermore, while the prior art seal member is attached to the inner surface of the housing, wrinkles may be formed in the seal member. This may result in a space, from which toner may leak, forming between an adhesive surface of the seal member and the inner surface of the housing.